内向整流钾通道在髓鞘发育及损伤修复中的作用及机制

Differentiation of oligodendrocyte precursor cells (OPC) into oligodendrocytes (OL) is a crucial step for the myelin formation in the central nervous system. Thus, investigation of the regulatory mechanisms of OPC differentiation and myelin formation is very important to myelin-related diseases and the repair of myelin injury. Recent research from New England Journal of Medicine showed that inwardly rectifying K channel Kir4.1 abnormally expressed in multiple sclerosis (MS), but its mechanism is unclear. Our preliminary data showed that Kir4.1 current exists in OPC and OL. Inhibiting Kir4.1 channel suppressed the expression of myelin proteins, indicating that Kir4.1 may play an important role in regulating OPC differentiation and myelin formation and myelin injury and repair. In this project, we will continue to study how Kir4.1 regulates the differentiation of OPC and the development of myelin using combined techniques including biochemistry, immunocytochemistry, electron microscope and electrophysiology et al. by interfering Kir4.1 expression in primary cultured OPC cells and Kir4.1 cconditional knockout mouse model. We will also study the role of Kir4.1 in myelin injury and repair by building mouse demyelination models. This project will provide new potential treatment targets for myelin-related diseases and the new drug screening.

少突胶质前体细胞（OPC）分化为成熟的少突胶质细胞（OL）是神经元髓鞘发育的重要环节。研究OPC分化与髓鞘发育的调控对于髓鞘损伤的防治和修复具有重要意义，但目前OPC发育与髓鞘损伤修复的机制仍不清楚。最近新英格兰医学杂志报道Kir4.1通道在多发性硬化症表达异常，但其机制未见报道。我们前期实验在OPC和OL中记录到Kir4.1电流，抑制Kir4.1通道活性显著降低髓鞘蛋白表达，提示Kir4.1可能在OPC分化、髓鞘发育及损伤修复中有重要作用。本项目在前期基础上，通过在培养细胞干扰Kir4.1表达和建立Kir4.1条件性基因敲除小鼠模型，结合生物化学、RNA干扰、免疫荧光染色、电镜、神经电生理等多种方法研究Kir4.1通道在OPC分化和髓鞘发育中的作用及机制，并利用小鼠脱髓鞘模型研究Kir4.1在髓鞘损伤修复和再生中的作用。本课题的研究将为髓鞘相关疾病的治疗及新药的筛选鉴定提供潜在的新靶点。

髓鞘再生和损伤修复是神经损伤修复的一个重要课题。少突胶质前体细胞（OPC）分化为成熟的少突胶质细胞（OL）是神经元髓鞘发育的重要环节。目前关于OPC分化和髓鞘发育机制的研究涉及面很窄，更多的相关信号分子有待研究。关于离子通道在OPC分化和髓鞘发育中的作用的研究还很少。我们的研究表明Kir4.1在OPC和OL中均有表达，并且在OPC分化为OL过程中Kir4.1表达上调，说明Kir4.1在少突胶质细胞发育中可能具有重要功能。电生理实验在OPC和OL中都记录到Kir4.1电流，并证明了OPC 上的钾通道主要是 Kir4.1 通道。体外抑制Kir4.1通道促进了OPC的增殖，抑制其分化，提示Kir4.1可能在OPC分化、髓鞘发育中有重要作用。在少突胶质细胞系中特异敲除Kir4.1通道的遗传修饰小鼠中，海马和皮层OL数目显著减少，胼胝体和视神经髓鞘相关蛋白MBP的表达降低，髓鞘形态异常，发育不完全，髓鞘形成明显受到了抑制作用。本课题的研究将为髓鞘相关疾病的治疗及新药的筛选鉴定提供潜在的新靶点。